Protection [Prot] Paladins tank through reactive damage.
That's a pretty interesting sentence, so let me explain what it means.
Prot Paladins cause aggro and threat by essentially taking damage. Yes, that's right. By taking damage.
Whilst other tanks have a rage bar that allows them to use abilities that cause monsters to single them out and beat on them, paladins have a mana bar that they use to cause holy damage to gain the attention of monsters and then shield spells that reflect damage when they are hit.
It's pretty fun to tank as a Protection Paladin because you can be surrounded by monsters and know you will kill them not because of anything you are doing but because you know that every time they hit you they will be damaged. Ergo, all you have to do is keep yourself healed and keep those shield spells up and the monsters will both be captivated by your damaging them AND by the threat of the damage that is being caused by them hitting you.
The problem comes when you are playing with a group of people that have no idea how a Protection Paladin functions (and let me tell you - this accounts for 4 in 5 WoW players).
I was doing a dungeon a few days ago with B-I-L who is geared for heroic instances (they're a
harder level of the same maps) so I knew the chances of my dying was fairly remote. But what irked me was when the DPS (yes them again) attacked straight away, casting spells, firing arrows, using pets - without giving me the chance to gain the acquaintance of the monsters.
Politely warning them that they need to give me a few seconds extra to pick up the slack got me a polite "sure". That particular group worked well, and apart from a few silly deaths, we managed to get through the whole thing fairly quickly.
But, of course, MY understanding of how Prot Paladins operate has only come about because I'm now playing one, which means that essentially until players try playing a tank, they will never learn what a tank is used for, or how to function around one.